Step 10: Switchable Devices

What This Version Does

A battered radio in the supply room can be switched on and off. It plays zoo-themed music when on, and powers down when off. It's bolted to the shelf so you can't take it.

What's New (Compared to V9)

V8 introduced SwitchableTrait alongside LightSourceTrait for the flashlight. V10 shows SwitchableTrait on its own — a device with on/off state that isn't a light source.

What You'll Learn

SwitchableTrait Standalone

SwitchableTrait gives any entity a toggleable on/off state:

radio.add(new SwitchableTrait({
  isOn: false,   // Starts off
}));

The player uses switch on radio or turn on radio to toggle it. The stdlib handles the switching action automatically.

SwitchableTrait vs OpenableTrait

These two traits look similar but serve different semantic purposes:

The parser routes switch on X to SwitchableTrait and open X to OpenableTrait. You'd never "switch on" a door or "open" a radio.

Trait Combinations with SwitchableTrait

SwitchableTrait combines naturally with other traits:

Common Verbs

All of these work for SwitchableTrait:

• switch on radio
• switch off radio
• turn on radio
• turn off radio

Commands to Try

> take keycard; south; unlock gate with keycard; open gate; south
> examine radio           See the radio
> switch on radio         Turn it on
> switch off radio        Turn it off
> take radio              Can't — scenery

The Code

See src/v10.ts for the complete, commented source.

Key Takeaway

SwitchableTrait gives entities an on/off toggle. It works standalone for simple devices (radio) or combined with LightSourceTrait for lights (flashlight). The switch on/off and turn on/off verbs are handled by stdlib automatically.